Universal centering vise



Oct. 7, 1952 F, SKAY 2,612,821

UNIERSAL. CENTERING vIsE Filed June s, 1948l Er-Eni- FRANKSKAV /l A INVENTOR.

Ei@ sa@ ,r BY n' W ATTORNEYS Patented Oct. 7, 1952 TENT OFFICE y iJNvEnsAL-CENTERING visa Frank Skay,` Detroit, Mich.; Aassigner to Ford Motor Company, Dearborn, Mich., a corporai tion of Delaware` f y appliationiuns, 1948, serialNo. 31,301

This invention relates to the machine tool art and is more particularly concerned withk a `universal centering vise w hlch 1nay` be employed to clamp a large Variety of articles sothat they may be machined in a'precisely predetermined position without distortion. .1 1

In the routine production of large numbersof duplicate parts, much trouble has beenencountered in properly securing, parts prior to-machining. This difficulty has been; especially troublesome in the case oi objects which have one dimension relatively large comparedl to the other dimensions and the weight andthe rigidity` of; the object. Such a part is. diiiicult to secure rigidly without distortion. example of such-apart is a transmission extension housing which is designed to be bolted againstthe rear-face of an automotive transmission housing. This part is an elongated roughly4 cylindrical casting with relatively thin walls land belled out at oneend. As this part is now produced,the belled end is rst faced off in a plane normal to` the axis of the casting. In the same operation a bearing seat designed to accommodate an antifriction bearing is machined near the top of the bell. A similar bearing seat must also be provided at the other end of the transmission extensionhousing Figure l isasectional viewA of applicants universalcentering visehin the open position. y

Figure 2 is' the same View of applicants universal centering vise exceptthat the parts have been mcved'to vshow this centering vise in the closed or working position and in which one of the parts Vto beclamped is eccentric.

In the figures on the drawing, the outline of y. the parts to be held have Lbeen indicated in phanand must be coaxial with the bearing located adjacent the bell within very narrow limits. In machining the second bearing seat, it has been the practice to clamp4 the parten a smooth bearing plate against the faced oi surface on the bottom portion of the bell'and to properly locate the part by means of holeswhich are provided in the faced oli portion for the purpose of attachl ing the transmission housing vextension to the transmission casing.

tom'by the dotted circles `I0..g-'In actual operation, the 'workpieces It] are clamped between jaws II and taperedlblocks- I2. When the workpieces lil havefbeen insertedbetween jaws II and tapered blocks"`"l2, as shown in Figure l, clearances 29 exist between workpieces l0 and vthe jaws I I and between the workpieces II) and tapered blocksl I2. When the work has' been so positioned,'the operator applies `a wrench to nut I3 and rotatesthis nut'o'nbolt I4. Boltldat its inner end merges Due to the length oi this part, there lis a substantial distance betWeen'the point at which it is initially clamped 'and located and the point at which machining must be done. To avoid tool chatter it has been found necessary to support this part adjacent the area Where the bearing seat is to be machined. This is necessary because the stresses incident to machining will appre-v ciably flex this long thin part. In spite of the exercise of great care in facing off the bell and drilling the locating bolt holes, it will be found that efforts to secure the bearing surface to be machined at the other end ofthe part prior to machining by any conventional clamping meansA almost invariably result in a suicient ilexing of the part along its axis to render the axes of the two bearings both eccentric and nonparallel. Y To correct this type of distortion has required a greater expenditure of timeby far than theactual machining operation. This is due to the fact that into keystone member I5, the purpose of which will become apparent as the description proceeds. As'nut I3 is rotated, jawsII advance toward workpieces I0 until actual Contact has been made with workpiece, I0 and clearance 29 between workpiece I0 and'jaw Il lhas disappeared.

' Secured to keystone member I5is rod Iltermihating in head'l which 4operates in bore'ISfin an inner saddle 20. Bore I9 outside `of head .IIBr

is substantially filled rkwitha' cylindrical block of elastomer 26 which is'also restrainedby face plate 3l which is secured to inner saddlef20.l At either endof inner saddle 20 are provided pivots 22 to which are secured clamping vblock I6. `In the center portion ofinnersaddle 20 islccated pivot 2| to which is secured outer-saddle 23; At each extremity of outer saddle 23 is provided pivots 25 by which arefsecuredv rockers 24. These rockers are-"somewhat bifurcated metal pieces` in which substantial forces must be employed to vclamp each tine normally rests upon a single tapered block I2.--Tape'red blocks I2 are restrained against lateral movement on one side by clamping blocks' IB and on the'other side by side plates 2l. These tapered blocksI I2 Aarealso 'guided to some extent by front'plate 30.

3 The operation of this device may be outlined as follows: At the beginning of the operation, the

attendant places the workpieces in the position shown in Figure 1; these workpieces having been initially secured at a. position remote from that shown in the drawing. In the case of the transmission extension housing, the pieces are initially secured by clamping the faced oi end of the bell against a ground plate on the machine. This places the remote and cylindrical end of the part in the desired position as shown in Figure 1.

When so secured, it will be noted that 'substantial clearance 28 exists between the workpieces I and jaws l l and between the workpiece I0 and tapered'blocks I2. It is of course desiredto Aclamp workpieces I0 in precisely the position shown in Figure 1 without in any manner moving these workpieces from the position shown. To accom- `p1ish this end, nut I3 is rotated on bolt Il las described above, wh`ich 'caus`es -jaws 'II to advance towards workpieces Ill until 'the clearances 29 existing between workpieces I0 and jaws II have disappeared entirely. When these clearances have disappeared further rotation of nut I3 will "cause keystone member I5, lrod II, inner saddle 20, outer 4saddle 23, rockers 24, and tapered blocks I2 to fadfva'nceto'wrds the workpieces I0. At this Atiine attention is particularly' invited to the clearances 28 which exist between the nonparallel sides of keystone lmember I5 and the adjacent sides of clampingblocks I6. Attention' is also directed to the fact that movement 'can be transmitted 'from-'rod I1 to 'inner saddle 20, outer saddle 23, Arockers 24, 'and tapered blocks I2 only by compression ofV bleek-of elastomer 26. The size and relationship of the various parts ineludingworkpieces I0 are so vchosen 'that the tapered blocks I2 will comefinto contact with the workpieces before the clearances 28 have been obliterated bythe outward movement 'of keystone niember I 5. When all lof the clearances 23 have been eliminated, a metallic contact exists between'the workpiece nIll and jaws I I and between workpieces I 0 and each of the tapered blocks I2. vHowever, clearances 28 still exist and further tighteningof nut I3 causes a substantial tension to bepro-v duced in r'od I] by `virtue of compression of block of elastomer 2t-` This pressure is of course ldans`v Knitted through inner saddle 20, outer .Sadd1ef23 and rockers 24 totapered blocks I 2 and results in 'a progresslv'ely'greater pressure against the workpiece.' However, it will be noted thatthis isfa balanced pressure and does not 'tend to move the centers of workpieces I0. When the proper pressure: 'been vbla' i'r'fed by the omprss'ion'f'blck of el'stf' 2 6, v'the clearances 28A between keystoie'mbr I5 and clamping members I B disappear and Atal-'tometal contact is established between these parte. A further tightening of nut I3 results in a latf eral thrust against clnpigbloks It ,by the nonparallel faces of keystone member I 5 Clamping blocks I6 are of course piveted at 22 in inner saddle 20 and tend to rotate slightly against the inner iacesoi innertapered blocks I2. By virtue of the mechanical advantage inherent in the nut I3 and the slope of the vnon parallel sides of keystone member I5, a very, high value of lateral thrustagainst tapered blocks I2 is obtained. This thrust secures tapered blocks I2 in the clamped position without the necessity of .applying further direct pressure against workpieces I0. c o A,

vlt is of course yvital in settingupnauniversal centering vise of this type that thel properrela-f' 4 tionship be maintained between the various parte so that clamping through clamping blocks I6 occurs before excessive pressures are produced by the jaws II acting against workpieces II). It is of course understood that instead of elastomer block 2liI other lresilient means such as springs could b'e substituted. Attention is invited to Figure 2 in which the action of this device is illustrated when the work- 'pieces are eccentric or of nonuniiorm size. The left-hand workpiece in Figure 2 is of the desired size 'andfsliapeiand concentric with the normal position offthe universal centering vise. It willbe' oted'that'each of the left-hand tapered blocks rI2 have advanced to the same degree and that left-hand rocker 24 has its parts substantially "aligned with the vremainder of the device. The right-handworkpiece I0, shown in Figure 2, fis'fnot of- 'the desired 'egulafr l"s h'ape end 'sizebut is, `'n e'verthe'le's's, l'c'z'ap"able of lin'gelaned without 'dim'culty i'n pplieants'devie. AVIn 'this case, the right-hand 'tapered blo'c'k I 2 '-l"1as fadvaned much'-further than 'the leftha`nd blekei the right-hand tapered blo"ck's I2. Ivhi'sis 4possible due 'to the 'factfthat 'rockers 24 f"are 'pivotally mounted on outer ysaddle l23 "nfd also because outer saddle 23 isfpivotdfntb inner 'saddle 2 `0 B y'virtue of thisI type or onstrution, it 'vv'illbe seen that applieant is enabled to Cl'ampwithO'ut adjustment andl in a precisely predetermined position all'similar that are within ordinary mmefauiminiv1ngt the .sesso 'of ree sorting 'to'precisi'qi1 measurements o'r e'c'ting machining operations,

Applicants' invention 'has been dseribe'd speeiflcally with regardto a lnp'ing device c apabl'e ,of "simultanei-'slsf geen: we, ansi@ be machined. `-It isv to `b e understooithat the invennon isnot sc iiniitee, but jean by the exercise jor ordinarymechania-l kill be readily adapted to theI clamping'of a single part or ni'ore than two parte'. Y t

the ensftomfer body.

sr'rAY RFRENCES errar) The following referenties' are of rcor'd :in the of this' patent: un'rrfnsTATs PA'fs 

